Piston rod connection for drop hammers



April 2, 1940.

w. H. J. FITZGERALD El AL PISTON ROD CONNECTION FOR DROP HAMMERS Filed July 8,

Fig.1.

1937 2 Sheets-Sheet 1 lnven'rors.

William H.\J.FiT3gerol d Reginald P'Filggerqld WWW&W

ATTys.

April 2, 1940- w. H. J. FITZGERALD ET AL 2,195,644

PISTON ROD CONNECTION FOR DROP HAMMERS Filed July 8, 1937 2 Sheets-Sheet 2 l4 Invenfors.

Wil liclm HQ. FiTggera Id 12 J2 Reginald F. Fi'fggerold b mxflwecm ATTys.

Patented Apr. 2, 1940 UNITED STATES PISTON ROD FFECE CONNECTION son DROP HAMMERS Application July 8, 1937, Serial No.'152,545 v 2 Claims.

This invention relates to improvements in drop hammer constructions comprising a cylinder and piston mounted upon the superstructure of the frame of the machine and having a piston rod directly connecting the piston to the hammer and operable when fluid under pressure is introduced into thelo'werchamher of the cylinder to lift the hammer and when released therefrom to permit the hammer to drop.

The invention comprises certain improvements upon the construction disclosed in Patent No. 1,924,545 granted to us August 29, 1933, and comprises a novel fluid pressure lifting mechanism including a novel piston firmly secured to the upper end of the piston rod and novel mechanism for securing the hammer to the piston rod.

In the operation of drop hammers the repeated jars produced by the impact of the hammer upon the anvil tends to loosen the connection between a. the piston and piston rod, and also between the hammer and the means by which it is secured to the piston rod, and the object of the present invention is to provide a novel piston construction which will reliably prevent it from becoming loosened upon the piston rod, or if loosened a construction which can be readily adjusted firmly to produce proper engagement therebetween, and also detachable means for firmly con- I necting the hammer to the piston rod which likev wise may be readily adjusted if any looseness of the connection is produced.

A further object of the invention is to provide improved means for cushioning the jar produced by the rebound of the hammer upon the piston rod.

These and other objects and features of the invention will more fully appear from the following description and the accompanying drawings and will be particularly pointed out in the m claims.

A preferred embodiment of the invention is illustrated in the accompanying drawings, in which,

Fig. 1 is a View mainly in vertical section of portions of the hammer, one of the guiding columns for the hammer, and a portion of the lifting cylinder, showing the improved piston and piston rod mechanism and means for securing 50 the piston rod to thehammer;

Fig, 2 is a detail vertical sectional view of the piston assembled upon the piston rod, the piston rod being shown in elevation;

Fig. 3 is a plan view of the construction illusu trated in Fig. 2;

Fig. 4 is an underneath plan view of the construction illustrated in Fig. 3; i

Fig. 5 is a vertical view, mainly in section, taken at right angles to that illustrated in Fig. 1, and

showing the connection between the lower end and particularly as the invention relates to improvements in drop hammer constructions disclosed in our prior patent aforesaid, only so much of the drop hammer mechanism as embodies the present invention is illustrated in the accompanying drawings.

The drop hammer construction illustrated in Fig. 1 comprises a hammer l, which is reciprocably mounted upon vertical guiding columns 2, one of which is shown, each of the ends of the hammer being provided with two or more extensions S which are counterbored from the upper end nearly to the lower end thereof to receive a bushing 4 of bronze or other relatively soft metal which is adapted tobe progressively con-j densed by the repeated blows of the hammer, r

thereby to maintain accurate guiding movement of the hammer as disclosed in our prior patent aforesaid. Means for lifting the hammer comprises a cylinder 5 which is mounted upon the superstructure of the machine and provided with a piston which is connected by a piston rod 6 directly to the hammer.

One ofthe principal features of the invention is to provide a piston of novel construction which is securely anchored to the upper end of the piston rod in such manner that it will not be loosened by repeated jars transmitted thereto from the impact of the hammer.

In the construction illustrated the piston rod 6 is provided with-a reduced portion 7 adjacent its upper end which presents shoulders 8 and 9 against which the parts of the piston are securely clamped both at the top and bottom. The piston comprises a head formed in two semicircular sections ill and l I having central semicircular apertures adapted to fit upon thereduced portion 7 of the piston rod so that the lower face of the head will abut against the shoulder 8. The head is provided with strengthening ribs l2 and I3 extending at right angles to each other,

the ribs I2 of adjacent sections being in the form of bosses adapted to be clamped together by screws I 4. The assembled head sections Ill and H of the piston head are provided with an annular recess l5 to receive the horizontal portion iii of a cup packing, the flange H of which tightly fits the wall of the cylinder. The head also is provided with an upwardly extending boss I 8 of smaller diameter than the recess l5 and an integral ring 19 is mounted upon the boss 18 and is of greater thickness than the height of the boss I8.

A pair of preferably semi-circular plates 20 are mounted upon the ring l9 and provided with extensions 2| which fit within the upper portion of the ring l9 and contact or nearly contact with the upper end of the boss l8. The plates 20 are provided with downwardly and outwardly inclined surfaces 22 and preferably semi-circular clamping members 23 and 24 having respectively inclined lower surfaces 25 complementary to and resting upon the surfaces 22 are interposed between the sections of the plate 20 and the upper shoulder 9 on the piston rod. The adjacent edges of the clamping members 23 and 24 are slightly spaced apart and the clamping members are connected together by means of screws 26, the plate 23 being countersunk to receive the heads of the screws 26.

By reason of this construction the piston can be readily assembled upon the piston rod by first clamping the sections of the head upon the reduced portion of the piston rod, then placing the cup packing IS in the recess 55, then placing the ring upon the upwardly extending boss l8 of the head, then inserting the extensions 2| of the plates 2!! into the central recess of the ring and placing the sections 23 and 25 upon the sections 21!, and finally tightly setting up the screws 26. When the screws 26 are thus set up tightly the complementary faces 25 of the sections of the clamping member will ride upon the complementary faces 22 of the plate 20, thereby forcing the clamping sections 23 and 24 against the upper shoulder 9 of the piston rod, and consequently forcing the lower. face of the piston head firmly against the shoulder 8 of the piston rod, thus firmly clamping the ring and packing and piston head against the shoulder 8 of the piston rod. By reason of this construction the piston is so securely anchored to the piston rod that it will not become loosened by the repeated jars transmitted to it by the impact of the piston.

A further object of the invention is to provide novel breechblock mechanism for securing the hammer to the piston rod. The hammer l is provided with a vertical bore 21 which extends downwardly from the central upper portion of the hammer a suitable distance into the hammer. The lower portion of the bore desirably is provided with a sleeve 28, preferably of bronze, and the piston rod 6 has at its lower end a head 29 of somewhat smaller diameter than the sleeve 28 in order to provide a more or less flexible connection between the hammer and the piston rod which will permit the hammer to move freely upon its columns or guide without any binding action resulting from misalinement of the axis of the piston with the vertical axis of movement of the hammer.

The hammer is provided near its upper end with horizontal drifts or recesses 30 extending laterally from the bore 2'! and providing preferably a rectangular recess for the breechblock. The breechblock of the present invention is of novel construction and comprises a lower section formed of complementary, preferably rectangular, plates 3! and 32 each having a downwardly projecting semicircular boss 33 adapted to fit within the sleeve 28 and having outwardly and downwardly inclined faces 34. The central portion of each of the plates 3! and 32 are provided with semi-circular apertures of slightly larger radius than that of the piston rod to permit universal movement between the hammer and piston as may be necessary to compensate for the misaline- 'ment above mentioned.

Clamping plates 35 and 36 of suitable thickness to fill the remainder of the breech-receiving recess 30 have lower downwardly and outwardly inclined faces complementary to and resting upon the faces 34 of the plates 31 and 32. The plates 35 and 36 have central semi-circular recesses of slightly larger diameter than the piston rod to permit relative movement between the hammer and the piston rod, as aforesaid. Suitable means, such as screws 37, are provided for drawing the plates 35 and 36 toward each other, thereby forcing the upper faces of the clamping plates 35 and 36 firmly against the upper wall of the breechblock recess and consequently forcing the lower faces of the plates 3! and 32 firmly against the lower wall of the breechblock recess. By reason therefore of this sectional breechblock construction the breechblock can be firmly clamped in its recess in such manner as to be immune from loosening by reason of the vibration transmitted to it upon impact of the hammer.

Suitable means, such as leather washers or washers of fibrous material 38, are interposed between the upper face of the enlarged piston head 29 and the under surface of the breechblock to avoid metal-to-metal contact therebetween and to provide suflicient yield between the hammer and the piston rod to avoid binding action of the hammer upon its guides.

Suitable means are also provided for cushioning the rebound of the hammer upon the lower face of the enlarged head 29 of the piston rod. In

previous constructions, such as illustrated in our cal bore in the hammer and having spheroidal upper and lower faces 40 and 4| which engage complementary faces in disks 42 and 43 which fit within the sleeve 28. Other disks 44 and 45 of relatively inelastic material such as leather desirably are interposed between the disks 42 and the lower face of the head 29 and between the disk 43 and the bottom of the bore 21, as shown more particularly in Fig. 5.

It has been found by experience that where an elastic cushioning member of general cylindrical form of the character above described is employed, more effective cushioning action is produced than in previous constructions and that permanent distortion or rupturing of the cushioning member is substantially eliminated.

By reason of the construction above described a fluid pressure lifting mechanism for drop hammers is provided in which loosening of the piston rods from the hammer and piston is effectively overcome and a more efficiently operating drop hammer mechanism of longer longevity is prothe inclined faces of'the lower plate sections, and

duced. v

It is obvious that the construction is such that any of the parts may be readily removed and replaced or adjusted with a minimum of expense.

It will be understood that the particular embodiment of the invention shown and described herein is of an illustrative character and that various modifications in construction may be made which embody the principles herein set forth within the meaning and scope of the following claims.

Having thus described the invention, what is head of said piston rod and provided with 2. rectangular horizontal breechblock recess of greater width than said bore in proximity to the upper end of said bore, a breechblock in said recess comprisim; a lower plate formed in sections loose- 1y embracing said piston rod and having semicircular bosses extending into said bore to premeans for forcing the sections of the upper plate toward each other thereby to clamp said upper and lower plates firmly against the upper and lower walls of said recess.

2. Fluid pressure lifting mechanism for a drop hammer construction comprising a cylinder and a piston therefor having a piston rod provided at its lower end with an enlarged head, a hammer having a central vertical bore to receive the head of said piston rod and provided with a rectangular horizontal breechblock recess of greater width than said bore in proximity to the upper end of said bore,:a breechblock in said recess comprising upper and lower pairs of sectional plates mounted in said recess loosely embracing said piston rod and having complementary inclined contacting faces, means for adjusting the sections of one of said pairs of plates toward each" other thereby to clamp said plates firmly against the upper and lower walls'of said recess, slightly elastic cushioning means interposed between the enlarged head of said piston and said breechblock to prevent metal to'metal contact, and a cylindrical mass of highly elastic rubber of substantially smaller diameter than said bore and having its upper and lower spheroidal ends seated in complementary sockets in disksof relatively less elastic material interposed between the lower end of said head and the bottom of said bore.

WILLIAM H. J FITZGERALD.

REGINALD P. FITZGERALD. 

